Technical Field
The present disclosure relates to a polyamide 56 fiber and a method for manufacturing the same. More particularly, the present disclosure relates to a dull polyamide 56 fiber and a method for manufacturing the same.
Description of Related Art
A polyamide refers to a polymer formed from monomers having a carboxyl group and monomers having an amino group polymerized via an amide bond. The manufacturing process of the polyamide is sample, and the polyamide has excellent durability and strength. Thus, the polyamide is widely applied to a variety of fields, such as textiles, auto parts, electronics and food package. A polyamide 66 (also known as nylon 66) is a kind of polyamide, which is the product of the condensing polymerization of adipic acid and hexamethylenediamine. The polyamide 66 can be made into filaments easily, and the textiles made of the filaments are featured with excellent quality. As a result, the polyamide 66 has been the mainstream material in the field of textiles, and the manufacturing technique of the polyamide 66 fibers is well developed.
Among the synthetic monomers of the polyamide 66, the adipic acid can be synthesized by techniques of biocatalysis. However, the synthesis of the hexamethylenediamine still relies on petrochemical products. As the environmental issues arising from the soaring international oil prices, the depletion and the large consumption of the fossil resources, industries and scholars in related fields are actively seeking for diamine compounds synthesized by techniques of biology to replace the hexamethylenediamine, so that the polyamide made from the diamine compounds can meet the environmental demands.
It is known that one of the diamine compounds which can replace the hexamethylenediamine is pentanediamine. The pentanediamine can be obtained by the decarboxylation of the lysine which is occurred by catalyzing the lysine with a lysine decarboxylase. It is proved that the pentanediamine can be successfully synthesized by the technique of biology, which adopts Escherichia coli (abbreviated as E. coli) and Corynebacterium glutamicum as engineering bacteria. The pentanediamine can be further reacted with the adipic acid, succinic acid or sebacic acid so as to form a new material, such as polyamide 56, polyamide 54 or polyamide 510, which allows the polyamide to become a promising bioplastic material Among the aforementioned new materials, the polyamide 56 is regarded as an alternative of the polyamide 66 being the mainstream material in the field of textiles.
However, as one of the synthetic monomers of the polyamide 56, the pentanediamine has five carbon atoms, which is one less than that of the hexamethylenediamine. Accordingly, the polyamide 56 and the polyamide 66 have many different properties, such as melting point and crystallinity. Therefore, the conventional manufacturing technique of the polyamide 66 fibers cannot apply to manufacture the polyamide 56 fibers. Take the manufacture of semi-dull polyamide 56 fibers or full-dull polyamide 56 fibers as example, the conventional manufacturing technique of the semi-dull or full-dull polyamide 66 fibers is adding commercially available polyamide 6 chips which contains TiO2 during the polymerization process, whereby the resulting fibers are semi-dull or full-dull. However, the melting point of the commercially available polyamide 56 chips without TiO2 is about 256° C. The melting point of the commercially available polyamide 6 chips which contains TiO2 is about 220° C. A spinning temperature required by the polyamide 56 chips is different from that of the polyamide 6 chips (the spinning temperature refers to the temperature of the manifold and the spinning beam during the spinning process). When the spinning temperature is excessively high, a thermal decomposition of the plastic chips having a lower melting point may occur; when the spinning temperature is excessively low, the plastic chips having a higher melting point may melt incompletely. As a result, a phase separation of the resulting semi-dull polyamide 56 fibers or full-dull polyamide 56 fibers is generated. Thus, the resulting semi-dull polyamide 56 fibers or full-dull polyamide 56 fibers have poor uniformity and poor spinnability. Furthermore, the spinning conditions of the spinning process are mutually influenced by each other. Even only one spinning condition is changed, such as the spinning temperature, if the other spinning conditions do not adjusted accordingly, such as the relative viscosity in sulfuric acid and the moisture content, there is a high possibility that the resulting fibers have poor quality. Therefore, how to develop the spinning conditions suitable for the polyamide 56 so as to manufacture the polyamide 56 fibers meeting the demands is the goal of the related industries.